The isolation and structure elucidation of 1 from the Basidomycete fungus Baeospora myosura is described. This new ene-triyne antibiotic was most potent against Gram-positive bacteria, while it was less active against Gram-negative bacteria and a yeast. MICs against several strains of Staphylococcus aureus were as low as 0.001 microg/mL. Analogues of 1 that did not contain the ene-triyne moiety were inactive against all microorganisms tested. The isolation of this new natural product was complicated by the highly reactive nature of the conjugated terminal polyacetylene.